#include <fstream>
#include <queue>
using namespace std;
ifstream cin("darb.in");
ofstream cout("darb.out");
int n, x, y;
vector<vector<int>> graf;
vector<int> d;
void bfs(int node)
{
    queue<int> q;
    d[node] = 1;
    q.push(node);
    while(!q.empty())
    {
        node = q.front();
        q.pop();
        for(auto next:graf[node])
            if(!d[next])
            {
                d[next] = d[node] + 1;
                q.push(next);
            }
    }
}
int main()
{
    cin >> n;
    graf.assign(n+1, vector<int>());
    d.resize(n+1);
    for(int i=1; i<n; i++)
    {
        cin >> x >> y;
        graf[x].push_back(y);
        graf[y].push_back(x);
    }
    bfs(1);
    int maxi = -1, node, s=0;
    for(int i=1; i<=n; i++)
        if(maxi < d[i])
        {
            maxi = d[i];
            node = i;
        }
    s += maxi;
    maxi = -1;
    fill(d.begin(), d.end(), 0);
    bfs(node);
    for(int i=1; i<=n; i++)
        maxi = max(maxi, d[i]);
    s = maxi;
    cout << s;
    return 0;
}